ESXi as base for a virtualized NAS/SAN appliance (napp-in-one)

ESXi is a type-1 barebone virtualizer. It runs directly on hardware. Think of it like a bios extension to run systems like BSD, Linux, OSX, Solaris or Windows side by side.

You can manage single ESXi servers with a free Windows application (vsphere). After setup, ESXi comes with a 60 day trial of all commercial features. From your download you can request a final free key for unlimited usage of ESXi without the commercial add-ons.